1. Field of the Invention
The present invention generally relates to devices for occluding a tissue opening such as a patent foramen ovale (PFO) or shunt in the heart, the vascular system, etc. and particularly provides an occluder device deliverable via a catheter to the site of a tissue opening.
2. Description of the Related Art
The device of the subject invention, in all its embodiments, may be utilized for the occlusion of many types of tissue openings, such as septal defects and PFO, and the like. For the sake of clarity, the present invention may, at times, be described specifically in the context of occlusion of a PFO. This specific description, however, should not be taken to limit the scope of the possible applications of the present invention.
The term “patent foramen ovale” generally refers to the failure to close a normal opening between the left and right atria (i.e., upper chambers) of the heart. Typically, a foramen ovale is a flap-like opening between the left and right atria of the heart which persists long after birth. Commonly, the foramen ovale has one flap extending from the top of the atrial chamber and another flap extending from the bottom of the atrial chamber, wherein the two flaps meet or overlap each other. Specifically, a PFO is typically located between the atrial septum primum and secundum at the location of the fossa ovalis. The opening provides a path to allow blood to bypass the lungs in an unborn infant, since the lungs are not in use during that period. The foramen ovale typically becomes functionally closed after the birth of the infant due to greater pressure from the increased blood flow in the left atrium acting upon the flap. However, in humans, for example, as many as 1 in 5 people have foramen ovale that do not fully close. In the absence of other cardiac defects or unusual cardiac pressures, the open foramen ovale does not present a substantial problem. However, in patients having circulatory problems-wherein the pressure on the right side of the heart is increased, for example as the result of congenital heart disease, blood may begin to flow through the foramen ovale. This result may also occur, for example, in divers when experiencing an increase in pressure due to being under water. The presence of a significantly large PFO, a flap structure that cannot provide sufficient seal, or a significant increase in pressure can cause blood to shunt across the defect from the right atrium to the left atrium and hence on to the left ventricle, aorta, and brain. If the defect is not closed, the risk of stroke is increased. Shunting of blood from the left to the right side can also have negative, consequences, such as cardiac failure or hemoptysis.
Tissue openings have traditionally been corrected by open heart surgery which required the surgeon to open the chest of a patient and bypass the heart temporarily. The surgeon would then physically cut into the heart and suture the opening closed. In the case of larger defects, a patch of a biologically compatible material would be sewn onto the tissue to cover the opening. However, the risk of complications occurring during such an intricate procedure presents substantial problems that patients would rather avoid.
In order to avoid such complications and the long recovery times associated with open heart surgery, a variety of trans-catheter closure techniques have been implemented. In such techniques, an occluding device is delivered through a catheter to the site of the tissue opening. Once the occlusion device is positioned adjacent the opening, it must be attached to the tissue wall containing the opening in a manner that permits it to effectively block the passage of blood through the opening. Furthermore, the occlusion device must also adjust to the anatomy or structure of the PFO, commonly a tunnel like structure, the width and length of which varies substantially between patients. As has been documented in the literature, the trans-catheter techniques developed thus far have had drawbacks associated therewith.
For example, a variety of heretofore known devices require assembly at the situs of the tissue opening. That is to say separable or separate halves of the device are deployed and subsequently united so as to traverse or span the tissue opening in furtherance of closure. Some well known devices require threading or “buttoning” of the discrete device elements. Additionally, such devices require special delivery and/or deployment tools, making their utility less than desirable.
A further shortcoming in the art yet to be adequately and fully addressed is the issue of device positioning at the situs and, more particularly, re-positioning in furtherance of effectuating a proper seal of the tissue opening. Also not addressed is the ability to retrieve the device from the situs without damage thereto. Heretofore, known devices appear to evidence a broad functionality, namely that of occlusion, or more pointedly, plugging a tissue opening without a full or more developed functionality of the constituents or substructures of the device, e.g., a device which includes a single occluder reversibly secured in place by an anchor assembly.
Heretofore known self expanding devices tend to be structurally complex, expensive to produce and cumbersome to load, unload, and reliably position at the situs of a tissue opening, and insensitive to the variable requirements of the PFO tunnel geometry. The balance or tension between the structural integrity of the device, its “size” (e.g., bulk, rigidity, etc.), and ability to remain optimally positioned continues to be a critical consideration, cardiac devices being subject to the rhythmic pumping of the heart, on the order of 100,000 beats per day.
The present invention addresses the needs of the field, as well as other problems associated with the prior art. The present invention offers advantages over the prior art and solves problems associated therewith.